1. Field of the Invention
The present invention relates to a mobile display device and a mobile display system, and more particularly, to a mobile display device and a mobile display system capable of minimizing noise and electric power consumption which occur upon view switchovers in the mobile display device, and an image signal reproducing method of the mobile display device.
2. Description of the Related Art
In general, a computer system is provided with a display device, an input device, a processor, a memory, and a storage part for storing programs or Operating Systems. In such a computer system, a user has difficulties in doing his or her jobs when using the computer system beyond a certain distance. The user with a mobile notebook or a laptop computer undergoes the same difficulties, so the user has to stay close to a computer system connected with a display device all the time even when he or she surfs the web or watches moving pictures. As for such a problem, Microsoft Corporation has provided a smart display device which is a mobile display device receiving and sending video data in a wired or a wireless manner with a computer system.
FIG. 1 is a block diagram for conceptually showing a conventional mobile display system.
The mobile display system shown in FIG. 1 has a host computer 10 for outputting wired and wireless video signals, a docking station 20 for receiving and sending data in a wired manner with the host computer 10, and a mobile display device 30 detachably mounted to the docking station 20, for receiving a wireless video signal outputted from the host computer 10. The mobile display device 30 operates in a fashion similar to a display device provided for a general computer system, when mounted on the docking station 20. Meanwhile, the mobile display device 30 performs wireless communications with the host computer 10 when the mobile display device 30 is released from the docking station 20. The wireless communications are performed according to a communication code such as 802.11b, and the mobile display device 30 receives a wireless video signal sent from the host computer 10 and reproduces the video signal on a screen. At this time, if the mobile display device 30 is provided with a touch panel, a command can be simply executed through the touch panel, and, when the mobile display device 30 is used to surf the web, a user can use the mobile display device, carrying it with him or her, in a distance range in which communications are available with the host computer 10.
FIG. 2 is a block diagram for showing a conventional mobile display device 30.
The mobile display device shown in FIG. 2 has a wireless module 31, a wired module 32, a docking detector 33, a switching part 34, a switching controller 35, and a display panel 36.
The wireless module 31 receives a wireless input signal applied from the host computer 10, and decodes and converts the wireless input signal into video signal data2. Further, the wireless module 31 applies a control signal ctr2 to the display panel 36 through the switching part 34 to enable the display panel 36 when a video signal is sent to the display panel 36.
The wired module 32 receives a wired input signal applied from the host computer 10 when the mobile display part 30 is coupled with the docking station 20 shown in FIG. 1, decodes and converts the wired input signal into a video signal data1. The converted wired input signal data1 is applied to the display panel 36 for reproduction, and, like the wireless module 31, when the wired module 32 applies the video signal data1 to the display panel 36, the control signal ctr1 is also applied to the display panel 36 to enable the display panel 36.
The docking detector 33 detects whether the mobile display device 30 and the docking station 20 are coupled.
The switching part 34 selectively applies to the display panel 36 the video signals data1 and data2 and the control signals ctr1 and ctr2 respectively outputted from the wireless module 31 and the wired module 32 depending upon a result of the detection of the docking detector 33. For example, if the mobile display part 30 and the docking station 20 are coupled with each other as determined by the docking detector 33, the switching part 34 passes only the video signal data1 and the control signal ctr1 which are applied to the display panel 36 from the wired module 32, and, if the mobile display part 30 and the docking station 20 are released from each other, the switching part 34 passes only the video signal data2 and the control signal ctr1 which are applied to the display panel 36 from the wireless module 31.
The switching controller 35 applies to the wired module 32 and the wireless module 31 information on whether the docking station 20 and the mobile display part 30 are coupled with each other or released from each other, to thereby have the wired module 32 and the wireless module 31 share information for turning on or off the display panel 36. For example, if the docking station 20 and the mobile display device 30 are released from each other while the wired module 32 applies the video signal data1 to the display panel 36, the switching controller 35 receives the release state from the docking detector 33, notifies the wired module 32 of the release state, and enables the wireless module 31. Accordingly, the wired module 32 stops sending the video signal data1 to the display panel 36, and sends the control signal ctr1 to turn off the display panel 36. If the control signal ctr1 is completely sent from the wired module 32 to the display panel 36, the wired module 32 notifies the switching controller 35 of the complete transmission, and the switching controller 35 instructs the wireless module 31 to send the video signal data2 after the switching controller 35 is notified. The wireless module 31 applies the video signal data1 to the display panel 36 through the switching part 34 in response to the instruction of the switching controller 35, and also applies the control signal ctr2 to turn on the display panel 36. At this time, the switching controller 35 enables the switching part 34 to pass signals between the wireless module 31 and the display panel 36.
As stated above, the conventional mobile display device 30 has to have the switching controller 35 recognize the states of the wired module 32 and the wireless module 31 all the time.
That is, at the time when the wireless module 31 applies the video signal data2 to the display panel 36, the wired module 32 applies the control signal ctr1 to the display panel 36 to stop sending a video signal to the display panel 36, and notifies the wireless module 31 through the switching controller 35 of whether the application of the control signal ctr1 is completed, and, at the time when the wired module 32 is to apply the video signal to the display panel 36, the wireless module 31 applies the control signal ctr2 to stop sending the video signal data2 to the display panel 36, and notifies the wired module 32 of whether the application of the control signal ctr2 is completed. Accordingly, the wired module 32 and the wireless module 31 have to share information to recognize each other's states all the time, which increases the complexity of the mobile display device 30 and error possibility upon implementing the information sharing in hardware and software.
In general, the wireless module 31 includes a module (not shown) for communicating with the host computer 10 in the wireless manner, a decoding module (not shown) for decoding a received wireless input signal and producing a video signal, input/output ports (not shown) for recognizing the state of the wired module 32 through the switching controller 35, a processor (not shown) for controlling the above modules and ports, and a memory (not shown), and the wireless module 31 is driven by a built-in operating system such as Windows CE. Accordingly, in order for the wireless module 31 to keep recognizing the states of the wired module 32 through the switching controller 35, the wireless module 31 frequently receives an interrupt signal (not shown) corresponding to a time point at which the wired module 32 is turned on or off, and an interrupt signal (not shown) corresponding to a state of the wired module 32, which increases malfunction possibility in the wireless module 31. Further, since the video signal data2 of the wireless module 31 is applied to the display panel 36 after the video signal data1 applied to the display panel 36 from the wired module 32 is cut off and the wireless module 31 checks the cut-off of the video signal data1, switching noise occurs upon view switchovers of the wired module 32 and wireless module 31. The switching noise renders the screen gray since no video signal is applied to the display panel 36 for a certain period of time, and the switching noise mainly occurs when the video signals data1 and data2 outputted from the wireless module 31 and the wired module 32 are added in the display panel 36. Further, the mobile display part 30 is provided with all the wired module 32 and the wireless module 31, which causes a problem that the mobile display part 30 consumes unnecessary electric power in the wired module 32 when the mobile display part 30 is driven through the wireless module 31.